At 90%, metastases are the most common cause of death for cancer patients. The precise mechanisms of tumor growth have yet to be adequately clarified, however. Commercially available in-vitro models are based upon reservoir systems which in no way reflect the physiological in-vivo condition inside the blood capillaries. In this project, we introduce a microfluidic system that enables direct monitoring of tumor cells escaping from the blood vessel (extravasation), and permits the analysis of the continual effects of shear force, contacts with the capillary wall, flow pulsations and also the gradient-aligned chemotaxis of tumor cells. The system comprises two overlapping micro channels separated by a porous membrane. The upper channel closed by the membrane is colonized as a 3D vessel equivalent with endothelial cells. The escaping tumor cells are caught in the lower channel for subsequence analysis. Milling technology and soft lithography are deployed for structuring of the microchips. The characteristics of tumor cells marked with the GFP fluorescent marker are to be investigated with an inverse fluorescent microscope in regard to different parameters.